DRAINAGE SYSTEM IN INDIA

Drainage

 The Drainage system is an integrated system of tributaries and trunk stream which collect and funnel surface water to the sea, lake or some other body of water. The total area which contribute water to a single drainage system is known as a drainage basin.

Drainage Pattern 

Drainage pattern is design formed by arrangement of river and tributaries. it means spatial arrangement and form of the drainage system in terms of geometrical shapes, recharge determined by various factors

• The slope of the land
• The underlying rock structures
• Climatic condition of the area
• Geological time period
• Amount of water flowing
• Periodicity of the flow

Types of Drainage Patterns Dendritic Drainage Pattern:

Look like a tree and its branches. It develops in the regions having uniform rock structure with insignificant joints and faults. For Example: The rivers of the northern plains; Indus, Ganga and Brahmaputra.

• Parallel Drainage Pattern: It develops in regions of parallel, elongated landforms where there is a pronounced slope to the surface. Tributary streams tend to stretch out in a parallel-like fashion following the slope of the surface. For Ex: The rivers originating in the Western Ghats; Godavari, Kaveri, Krishna, and Tungabhadra.
• Trellis Drainage Pattern: Trellis is a rectangular pattern formed where two sets of structural controls occurs at right angles. In a trellis pattern, the river forms a net like system and the tributaries flow roughly parallel to each other. For Example: The old folded mountains of the Singhbhum (Chotanagpur Plateau) have a drainage of trellis pattern.
• Rectangular Drainage Pattern: The rectangular drainage pattern is found in regions that have undergone faulting. It develops on a strongly joined rocky terrain. Streams follow the path of least resistance and thus are concentrated in places where exposed rock is the weakest. The tributary streams make sharp bends and enter the main stream at high angles. For Example: Streams found in the Vindhya mountain range; Chambal, Betwa and Ken.
• Radial Drainage Pattern: It form when rivers originate from a hill and flow in all directions. For Example: The rivers originating from the Amarkantak.
• Centripetal Drainage Pattern: It is just the opposite of the radial as streams flow toward a central depression. During wetter portions of the year, these streams feed ephemeral lakes, which evaporate away during dry periods. For Example: Loktak lake in Manipur.

INDIAN DRAINAGE SYSTEM

Indian drainage system may be divided on the basis of discharge of water (orientations to the sea), it may be grouped into:

• The Arabian Sea drainage
• The Bay of Bengal drainage.
  

On the basis of mode of origin, nature, and characteristics, the Indian drainage is classified as

• The Himalayan drainage 
• The Peninsular drainag
  

The Himalayan Drainage

• The Himalayan drainage system has evolved through a long geological history.
• It mainly includes the Ganga, the Indus and the Brahmaputra river basins. Since these are fed both by melting of snow and precipitation, rivers of this system are perennial.
• The various geographical features made by the Himalayan rivers are:
  • In upper reaches (Youthful stage): Gorges, V-shaped valleys, rapids, waterfalls, truncated spurs etc.
  • In plane areas or middle part (Mature stage): While entering the plains, they form depositional features like flat valleys, ox-bow lakes, flood plains, braided channels, and deltas near the river mouth. Over the plains they display a strong meandering tendency and shift their courses frequently.
• The major river systems of Himalayan drainage are:
  • The Indus system
  • The Ganga system
  • The Brahmaputra system

Evolution of Himalayan Drainage system

• Theory: There was a mighty river called Shiwalik or Indo-Brahma traversed the entire longitudinal extent of the Himalaya from Assam to Punjab and onwards to Sind, and finally discharged into the Gulf of Sind near lower Punjab during the Miocene period some million years ago.
• Evidence: The remarkable continuity of the Shiwalik and its lacustrine origin and alluvial deposits consisting of sands, silt, clay, boulders and conglomerates support this viewpoint.
• Dismemberment of Rivers: Himalayan rivers later got dismembered into three major systems.
  • the Indus and its five tributaries in the western part;
  • the Ganga and its Himalayan tributaries in the central part; and
  • the stretch of the Brahmaputra in Assam and its Himalayan tributaries in the eastern part.
• Reason of dismemberment: This dismembered was probably due to the Pleistocene upheaval in the western Himalayas, including the uplift of the Potwar Plateau (Delhi Ridge), which acted as the water divide between the Indus and Ganga drainage systems.
• Ganga and Bharamputra east flow: Likewise, down-thrusting of Malda gap (Garo-Rajmahal Gap) area between Rajmahal hills and Meghalaya plateau during mid-Pleistocene period, diverted the Ganga and the Brahmaputra systems to flow towards the Bay of Bengal.

The Indus River System

• Coverage: It is one of the largest river basins of the world. A little over one-third of the Indus basin is located in India; in the states of Jammu & Kashmir, Himachal Pradesh and Punjab. The rest of the portion is in Pakistan.
• Origin: It originates from a glacier near Bokhar Chu in the Kailash Mountain range (Tibetan region). In Tibet, it is known as ‘SingiKhamban; or Lion’s mouth.
• The river-course:
  • The Indus cuts through Himalayas and enters India near Damchok.
  • flows in India only through the Leh district in Jammu and Kashmir.
  • It enters into Pakistan near Chillar in the Dardistan region through a deep gorge near the hair-pin bend of Nanga Parbat.
  • It finally discharges into the Arabian Sea, east of Karachi.
• Characteristics Features:
  • Largest number of glaciers: The Indus drains the largest number of glaciers of Himalayas, Ladakh, Zaskar, and Kailash.
  • Gentle slope: The Indus plain has a very gentle slope.
• Indus Water Treaty((WT): IWT is a water distribution treaty between India and Pakistan signed on September, 1960. The Treaty was signed by the then PM Jawaharlal Nehru and Pakistan’s president Ayub Khan. It was brokered by the World bank. The Indus water Treaty deals with river Indus and its five tributaries which are classified into categories
  • Eastern River: Sutlej, Beas, Ravi
  • Western river: Jhelum, Chenab, Indus
• Terms of Treaty: According to Treaty, all water of eastern river Shall be available for unrestricted-use in India. While, India should let unrestricted flow of water from Western rivers to Pakistan. It does not mean that India cannot use Western river water. The Treaty says that India can use the water in western rivers in non-consumptive needs. Non-consumptive means we can use it for irrigation storage and even for electricity production.
• In News: It has recently been in the news due to the disagreement about the construction of kishenganga and Ratle hydroelectric power plant being built by India.

The Ganga River System

• Coverage: The Ganga river system is the largest in India having a number of perennial and non-perennial rivers originating in the Himalayas in the north and the Peninsula in the south, respectively. It accounts for 26.3% of the geographical area of the country and is shared by ten states.

The river-course:

• The Ganga enters the plains at Haridwar.
• From here, it flows first to the south, then to the south-east direction to reach Allahabad. Here it is joined by the Yamuna.
• Further, near Rajmahal hills, Ganga turns south-east and bifurcates at Farakka into Bhagirathi – Hugli in West Bengal and as the Padma in Bangladesh.
• The river finally discharges itself into the Bay of Bengal near the Sagar Island.

Characteristic Features:

• Largest delta: The arcuate shaped delta of Ganga and Brahmaputra is world’s largest delta, 400km in length.
• Largest area: Uttarakhand and Uttar Pradesh occupy the largest area of Ganga river system i.e. 34.2%.
• Alluvial soil: Ganga river system make one of the most fertile lands of north India by depositing silts and forming alluvial soil.
• Sorrow of Bihar: Kosi, a tributary, is flood prone. So, it is known as “Sorrow of Bihar.”
• Ravines: The Chambal is famous for its badland topography called the Chambal ravines.
• Largest tributary: Yamuna is the largest and most important tributary.

Ganga Pollution Issue:

• Most polluted in the world: The Ganges was ranked as the fifth most polluted river of the world in 2007.
• Threat to species: Pollution threatens many fish species and amphibian species and the endangered Ganges river dolphin (Blind Dolphin).
• Religious bane: The water at Haridwar district face almost all parameters of safety according to official sources nearly one lakh devotees’ bath at the over 20 Ghats of Haridwar every day.
• BOD: The biological oxygen demand is already 6.4 mg per litre in the river water instead of 3 mg per litre which is normal and safe for bathing.
• Failure of Ganga Action Plan: The Ganga Action Plan, an environmental initiative to clean up the river, has been a major failure thus far, due to corruption, lack of technical expertise, poor environmental planning, and lack of support from religious authorities.

The Brahmaputra River System

• Origin: The Brahmaputra has its origin in the Chemayungdung glacier of the Kailash range near the Mansarovar lake. Mariam La separates the source of the Brahmaputra from the Manasarovar Lake.

The river-course:

• Most of the course of the Brahmaputra lies in Tibet, popularly known as Tsangpo. It flows eastwards parallel to the Himalayas. It receives a large number of tributaries in Tibet.
• After reaching Namcha Barwa, it takes a “U” turn (also known as Hair Pin turn) and enters India west of Sadiya town in Arunachal Pradesh through the deep Dihang or Siang gorge of Himalayas. Here initially it is called as Siang and then as Dihang.
• It is joined by Dibang, Lohit, Kenula and many other tributaries and finally forms the Brahmaputra in Assam.
• It then enters into Bangladesh near Dhubri and flows southward. In Bangladesh, the Tista joins it on its right bank from where the river is known as the Jamuna. [Note: The Tista was a tributary of the Ganga prior to the floods of 1787 after which it diverted its course eastwards to join the Brahmaputra.]
• The Jamuna and Ganga confluence at Goalundo and afterwards are called as the Padma. Further south, Padma is joined by Meghna (Barak river in India) and thence onward it is known as Meghna to finally merge in the Bay of Bengal.

Characteristic Features:

• Longer than Indus: River Brahmaputra is a little longer than the river Indus.
• Canyon: It forms a spectacular Grand Canyon – like canyon in Tibet.
• Largest riverine island: The river is nearly 16 km wide at Dibrugarh and forms many islands, the most important of which is Majuli. Majuli is the world’s largest riverine island and India’s first island district.
• Braided channel: The Brahmaputra has a braided channel. It carries a lot of silt and there is excessive meandering.
• Flood and erosion: The Brahmaputra is well-known for floods, channel shifting and bank erosion. This is due to the fact that most of its tributaries are large, and bring large quantity of sediments owing to heavy rainfall in its catchment area.

The Peninsular Drainage System

• Oldest system: The Peninsular drainage system is older than the Himalayan one. This is evident from the broad, largely-graded shallow valleys, and the maturity of the rivers.
• Concordant drainage: The peninsular drainage is mainly Concordant except for few rivers in the upper peninsular region.
• Non-perennial: They are non-perennial rivers with a maximum discharge in the rainy season.
• Mature stage: The peninsular rivers have reached mature stage {Fluvial Landforms} and have almost reached their base level. [Vertical down cutting is negligible] which are characterized by broad and shallow valleys.
• Have gentle slope: The river banks have gentle slopes except for a limited tract where faulting forms steep sides.
• WG act as water divide: The Western Ghats running close to the western coast act as the water divide between the major Peninsular Rivers, discharging their water in the Bay of Bengal and as small rivulets joining the Arabian Sea.
• Rivers that drain into Bay of Bengal: The Mahanadi, the Godavari, the Krishna, the Cauvery and several smaller rivers drain south-east into the Bay of Bengal.
• Rivers that drain into Arabian Sea: The Narmada, the Tapi, the Mahi flowing west as well as several small streams originating from the Western Ghats flow westwards into the Arabian Sea.
• Rivers that drain into the Ganges: Tributaries of the Ganga and the Yamuna such as the Chambal, the Betwa, the Ken, the Son, and the Damodar flow in the north-easterly direction.
• Characteristics: Peninsular rivers are characterized by a fixed course, absence of meanders, and nonperennial flow of water. The Narmada and the Tapi, which flow through the rift valley, are exceptions.

Evolution of Peninsular Drainage system

1. Theory 1
   • Geologists believe that the Sahyadri Aravali axis was the main water divide in the past.
   • According to one hypothesis, the existing peninsula is the remaining half of a bigger landmass.
   • The Western Ghats were located in the middle of this landmass.
   • One drainage was towards the east, flowing into the Bay of Bengal, and the other towards the west, draining into the Arabian Sea.
   • The western part of the Peninsula cracked and submerged in the Arabian Sea during the early Tertiary period (coinciding with the formation of the Himalayas).
   • During the collision of the Indian plate, the Peninsular block was subjected to subsidence in a few regions, creating a series of rifts (trough, faults).
   • The now west-flowing rivers of the Peninsula, namely the Narmada and the Tapi, flow through these rifts.
   • Evidence: Straight coastline, steep western slope of the Western Ghats, and the absence of delta formations on the western coast makes this theory a possibility.
2. Theory 2
   • It is believed that the west-flowing peninsular rivers do not flow in the valleys formed by the rivers themselves.
   • Rather, they have occupied two fault rifts in rocks running parallel to the Vindhyas.
   • These faults are supposed to be caused by a bend of the northern part of the Peninsula at the time of the upheaval of the Himalayas.
   • The Peninsular block, south of the cracks, tilted slightly eastwards during the event, thus giving the orientation to the entire drainage towards the Bay of Bengal.
   • Criticism: Tilting should have increased the gradient of the river valleys and caused some rejuvenation of the rivers. This type of phenomenon is absent in the Peninsula, barring a few exceptions such as waterfalls.

Difference Between Himalayan and Peninsular Rivers

RIVER REGIMES

Meaning: The pattern of the seasonal flow of water in a river is called its regime. The main difference in the flow pattern of the Himalayan and the Peninsular rivers is caused by the differences in climate.

1. Himalayan Rivers: The Himalayan rivers are perennial and their regimes are dependent on the pattern of water supply both from snow-melt and rainfall. Their regimes are monsoonal as well as glacial.
   • Ganga
     • The Ganga has its minimum flow during the January-June period.
     • The maximum flow is attained either in August or in September.
     • After September, there is a steady fall in the flow.
     • The river, thus, has a monsoon regime during the rainy season.
     • There are striking differences in the river regimes in the eastern and the western parts of the Ganga Basin.
     • The Ganga maintains a sizeable flow in the early part of summer due to snow melt before the monsoon rains begin.
     • The mean maximum discharge of the Ganga at Farakka is about 55,000 cusecs while the mean minimum is only 1,300 cusecs.
     • The two display interesting differences in their regimes compared to the Himalayan rivers.
2. Peninsular Rivers: The regime of most of the peninsular rivers, on the other hand, are only monsoonal as they are controlled by rainfall alone. The two peninsular rivers display interesting differences in their regimes compared to Himalayan rivers.
   • Narmada
     • The Narmada has a very low volume of discharge from January to July but it suddenly rises in August when the maximum flow is attained.
     • The fall in October is as spectacular as the rise in August.
     • The flow of water in the Narmada, as recorded at Garudeshwar, shows that the maximum flow is of the order of 2,300 cusecs, while the minimum flow is only 15 cusecs.
   • Godavari
     • The Godavari has the minimum discharge in May, and the maximum in July-August.
     • After August, there is a sharp fall in water flow although the volume of flow in October and November is higher than that in any of the months from January to May.
     • The mean maximum discharge of the Godavari at Polavaram is 3,200 cusecs while the mean minimum flow is only 50 cusecs.

INDUS WATER TREATY

Indus Waters Treaty, treaty, signed on September 19, 1960, between India and Pakistan and brokered by the World Bank. The treaty fixed and delimited the rights and obligations of both countries concerning the use of the waters of the Indus River system.

Points of Issues

• In 2016, Pakistan approached the World Bank raising concerns about India’s Kishenganga and Ratle hydroelectric power projects being constructed in Jammu & Kashmir.
• The Bulbul project (which is a navigation lock-cum-control structure at the mouth of the Wular Lake, situated on the Jhelum from Anantnag to Srinagar and Baramulla) was suspended in 1987 after Pakistan objected to it.

The utilization of Excess Water:

• Shahpurkandi Project: This will help in generating power for Punjab and Jammu & Kashmir.
• Ujh Multipurpose Project: This will create storage of water on the Ujh, which is a tributary of the River Ravi, for irrigation as well as power generation.
• 2nd Ravi Beas link: This has been declared a National Project by the GOI. This involves constructing a barrage across river Ravi for diverting water through a tunnel linked to the Beas Basin.

Provisions of the Treaty

• Division of Rivers: The treaty gave the waters of the western rivers—the Indus, Jhelum, and Chenab—to Pakistan and those of the eastern rivers—the Ravi, Beas, and Sutlej—to India.
• Permanent Commission: The commission’s duties include acting as a platform for the exchange of river-related information, for ongoing collaboration, and as the first port of call for conflict resolution.
• Indian Use of Western Rivers: Annexure D allows it to build ‘run of the river hydropower projects, meaning projects not requiring live storage of water. It also provides certain design specifications which India has to follow while developing such projects.
  • For Western Rivers, the treaty gives India 20% of the water from the Indus River System and the rest 80% to Pakistan.
• Dispute resolution: In accordance with the IWT’s three-step dispute resolution process, “Questions” on both sides can be addressed by the Permanent Commission or at the inter-government level.
  • In case of unresolved questions or “differences” either side can approach the World Bank to appoint a Neutral Expert (NE) to come to a decision.
• Exit Provisions: IWT does not have a unilateral exit provision and is supposed to remain in force unless both countries ratify another mutually agreed pact.

Issues/Concerns

• Pakistan’s Opposition: Over the past two decades Pakistan has launched multiple attempts to prevent India from building dams on both the Chenab and the Neelum rivers.
  • Example: Pakistanis also fear that India will use its upstream dams to control how much water flows down into Pakistan via the Indus.
• India’s Opposition: Pakistan’s Left Bank Outfall Drain (LBOD) project passes through the Rann of Kutch in India’s Gujarat. The project was constructed without India’s consent. India has objected because this is in contravention of the IWT.
• Water Security: The basic dissatisfaction is that the treaty prevents it from building any storage systems on the western rivers, even though it allows building storage systems under certain exceptional circumstances.
• Revision and Reform: The treaty was signed before the subsequent wars with Pakistan and also does not reflect the current geopolitical climate between India and Pakistan.
• Stalled Project: The Tulbul project (which is a navigation lock-cum-control structure at the mouth of the Wular Lake, situated on the Jhelum from Anantnag to Srinagar and Baramulla) was suspended in 1987 after Pakistan objected to it.
• Does not Address Climate Change: Present-day pressing issues such as climate change, global warming, and environmental impact assessment were not taken into account by the treaty.
• Underutilized: Indian utilization of the western rivers is underutilized, and the terms of exchange are more favorable to Pakistan.
• Need for renegotiation: Experts say that renegotiation can happen only when both parties see potential benefits from it, and in the current political climate, it may not be possible.
• Technical Nature: The treaty is highly technical, leading to far-ranging divergences between the two countries in terms of interpretations.
• Example: The treaty says that storage systems can be built but to a limited extent. However, the technical details make it difficult to conclude under what circumstances projects can be carried out.
• Bilateral Issues: A strong stance against Pakistan can hamper the country’s image internationally. India’s other neighboring countries like Bangladesh and Nepal may become skeptical about similar treaties with them.

Way Forward

• Joint Study Groups: A simple solution is to form a joint study group of experts who should function as a part of the mechanism available within the purview of the Indus Water Treaty on a bilateral basis.
• Optimize Potential: Article 7 of the Indus Water Treaty mentions ‘Future Cooperation,’ which, inter alia, discusses efforts in the future to optimize the potential of the Indus river system jointly.
• Use as a bargaining chip: India must use the terms of the treaty to bargain with Pakistan into stopping cross-border terrorism.
• Climate Change: There needs to be more holistic coverage of water sustainability and issues of climate change.

Parliamentary Standing Committee recommendations

• Reflect Climate Change: In view of contemporary issues like climate change, global warming, and environmental impact assessments, the government of India should revise the 1960 Indus Water Treaty with Pakistan.
• Institutional Framework: To address the effects of climate change on water supply in the Indus basin and other issues that are not covered by the Treaty, it is necessary to create some type of institutional structure or legislative framework.
• Canal Revision: In order to boost their water carrying capacity, it was also advised that the canal systems in Punjab and Rajasthan be renovated.

NATIONAL WATER GRID OR RIVER INTERLINKING PROJECT

Project: The National River Linking Project (NRLP), formally known as the National Perspective Plan, envisages the transfer of water from water ‘surplus’ basins where there is flooding, to water ‘deficit’ basins where there is drought/scarcity, through inter-basin water transfer projects.

Proposal

• South Asian Water Grid: The implementation of the NRLP will form a gigantic South Asian Water Grid with a network of nearly 3000 storage dams.
• Origin: The then Ministry of Irrigation prepared this plan of interlinking of rivers in August 1980.
• Concerned Agency: The NRLP is managed by National Water Development Agency (NWDA) under the Ministry of Jal Shakti.

Arguments in Favour of River Interlinking

• Control floods and droughts: India receives the majority of its rainfall in only 3 months of a year, i.e., from June to September. Most of such rainfall occurs in northern and eastern India, whereas southern India remains water deficit. Thus, linking will provide a two-way advantage, that is, controlling of floods as well as droughts.
• Solve the water crisis: The project envisages the supply of clean drinking water and water for industrial use amounting to 90 and 64.8 billion cu.m respectively with a view to satisfying the demand by 2050.
• Improve the inland navigation: Interlinking of rivers will create a network of navigation channels. Water transport is cheaper, less-polluting compared to the road and railways. Further, the interlinking of rivers can ease the pressure on railways and roads also.
• Dry Weather Flow Augmentation: Transfer of surplus water stored in reservoirs during monsoon and releasing it during the dry season will facilitate a minimum amount of dry weather flow in the rivers. This would help in pollution control, navigation, fisheries, growth of forests, protection of wildlife, etc.
• Development of power: The interlinked rivers have the potential to generate a total power of 34000 MW (34 GW). This will help India to reduce coal-based power plant usage. Furthermore, it will also help to achieve India’s Nationally Determined Contribution in the Paris Climate Agreement.
• Irrigation benefits: Indian agriculture is primarily dependent on monsoons, which is not reliable. The project claims to provide additional irrigation facilities of about 35 million hectares in the water-deficit western and peninsular regions.
• Commercial benefits: In the long run, canals can be utilized as inland waterways, which will help in faster movement of goods from one place to another. Moreover, rural areas will develop with diverse income sources such as fish farming, etc.
• Defense: The project is expected to strengthen the security of the country by an additional waterline of defense.

Arguments Against River Interlinking

• Project feasibility: The project is estimated to cost around Rs.5.6 lakh crores. Additionally, there is also the requirement of huge structures. All this requires a great engineering capacity. So, the cost and manpower requirement is immense.
• Environmental impact: The huge project will alter entire ecosystems. The wildlife, flora, and fauna of the river systems will suffer because of such displacements and modifications. Many national parks and sanctuaries fall within the river systems. All these considerations will have to be taken care of while implementing the project.
• Impact on society: Building dams and reservoirs will cause the displacement of a lot of people. This will cause a lot of agony for a lot of people. They will have to be rehabilitated and adequately compensated.
• Controlling floods: Although theoretically, it is possible, India’s experience has been different. There have been instances where big dams like Hirakud Dam, Damodar Dam, etc., have brought flooding to Odisha, West Bengal, etc.
• Political Challenges: Water is a state subject in India. So, the implementation of the NRLP primarily depends on Inter-State co-operation. Several states, including Kerala, Andhra Pradesh, Assam, and Sikkim, have already opposed the NRLP.
• International disputes: Countries like Bhutan, Nepal, and Bangladesh will be impacted due to the Interlinking of Rivers project.
  • For Example: Bangladesh strongly objects to transferring the Brahmaputra water to the Ganga. Considering this, the smooth implementation of the project is not expected.
• Other Challenges: The government is proposing a canal irrigation method for transmitting water from one area to another. The maintenance of canals is also a great challenge as it includes preventing sedimentation and clearing logging of waters, etc.

Way Forward with Interlinking of Rivers

• Local solutions: Like better irrigation practices and watershed management, should be focused on.
• Feasibility of case: The necessity and feasibility of river-interlinking should be seen on a case-to-case basis, with adequate emphasis on easing out federal issues.
• Concept of virtual water: Instead of interlinking rivers, India can try the concept of virtual water.
  • For Example: Suppose when a country imports one tonne of wheat instead of producing it domestically, it is saving about 1,300 cubic meters of the local water. The local water can be saved and used for other purposes.
• Integrated water resource management: India needs to conserve every drop of water, reduce wastage, equitable distribution of resources, and enhance groundwater simultaneously. Small-scale simple actions should be tried instead of large-scale projects.